Fluid operated switch



Dec. 12, 1961 J. RABINOW 3,013,134

FLUID OPERATED SWITCH Filed Sept. 30, 1958 2 Sheets-Sheet 1 INVENTOR JACOB RABINOW Dec. 12, 1961 J. RABINOW FLUID OPERATED SWITCH 2 Sheets-Sheet 2 Filed Sept. 30, 1958 FIG. 4

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switching rate potential of the fluid .design.

United States Patent Q 3,013,134 FLUID OPERATED SWITCH Jacob Rabinow, TaskomaPark, Md. (1603 Drexel St, Washington 12, D.C.) Filed Sept. 30, 1958, Ser. No. 764,443 6 Claims. (Cl. 290--81.9)

The present invention relates in general to electrical switches and more particularly concerns an improved fluid operated commutating switch having one or more complementary contact pairs which may be selectively and positively engaged for relatively brief intervals at exceedingly high switching rates. This application is a continuation-in-part of the copending application of Jacob Rabinow entitled Fluid Operated Switch, Serial No. 552,- 184, filed December 9, 1955, now Patent No. 2,855,473. The improved switches disclosed herein retain all of the advantages exhibited by the devices disclosed in the parent application While substantially improving performance through the elimination of the contact bounce, noise, and chatter customarily encountered in high speed mechanical commutating systems.

The earlier application disclosed a fluid operated switch having a number of arcuately arranged stationary contacts with a like number of conductive resilient fingerlike contact members extending over and into closely spaced relationship with a respective one of the stationary contacts. A nozzle was arranged to direct a stream of fluid under pressure upon one of the finger-like contacts to effect engagement with its complementary stationary contact. As the nozzle was swept across the finger-like members, these were sequentially engaged and resiliently separated from each respective fixed contact to achieve the desired commutating action.

Contact bounce, which in the electrical system translates into undesired noise, is a Well-known and fundamental problem in all switching apparatus. When two hard and unyielding substances are forcibly brought into contact, some bounce must result unless the kinetic energy is either absorbed in one of the materials causing permanent-deformation, or in some externally provided damping means. Although bounce may to some extent be tolerated in simple switches and relays, the most common technique for avoiding this problem is through the introduction of damping. This, however, while representing asolution, inherently reduces the maximum useful switching speed, thus limiting utility in modern high speed telemetering, instrumentation and like commutating applications.

The invention disclosed in the above-cited parent application represented a significant advance in the art of mechanical commutation, particularly insofar as it permitted a marked increase in reliable switching rates over apparatus theretofore available. Bounce of the resilient, finger-like contacts, however, imposed an upper limit on speed, and in essence, precluded realization of the full actuated contact Accordingly, the present invention contemplates and has as a primary object the provision of a high speed fluid actuated commutating switch generally embodying the principles of the parent application, wherein the contacts selected for connection are positively engaged in response to forces imparted by a fluid stream, virtually without bounce or chatter.

It-is another object of the invention to provide fluid 'ice A further object of the invention is to provide a compact, lightweight and high speed fluid-operated commutating switch of minimum complexity, and hence of relatively low initial cost.

It is a further object of the invention to provide a switch which may be initially adjusted with great ease to obtain bounce-free contact operation and which thereafter retains this adjustment, even after extended periods of continuous service.

It is another object of this invention to provide a fluid operated switch offering low contact wear despite the fact that considerable contact pressure is employed to achieve reliable electrical connection.

Broadly speaking, the novel switch comprises at least one pair of contacts with means responsive to a fluid stream for effecting relative velocity between the contacts generally in time quadrature with the force exerted by the fluid stream. As a result the contacts are engaged when the velocity therebetween is close to zero, the kinetic energy at the time of engagement being so low as to yield negligible bounce. I

In one embodiment of the invention, one contact is carried by a flexible, elongate member and the curvature or bowing, or the effective length of this member is controlled by the fluid stream to determine the relative displacement between the contacts. More specifically, the elongate member may be normally bowed when the contacts are separated. The pressure from a fluid stream causes this member to straighten and drive the contacts into engagement. When this fluid pressure is removed, pressure may in turn be applied in the opposite direction by another fluid stream, thus accelerating the return of the elongate member to its normally curved shape.

By arcuately arranging a plurality of these contact pairs, circularly sweeping fluid jets may be used to sequentially actuate the respective contact pairs at commutating speeds hitherto unavailable.

Other features, objects and advantages of the invention will become apparent from the following specification when read in connection with the accompanying drawing in which:

PEG. 1 is a plan view generally illustrating the novel commutating switch and auxiliary apparatus;

operated means for rapidly and positively disengaging opposed contacts after the fluid stream selecting such contacts. for engagement is no longer directed thereon.

Still another object of the invention is to achieve the foregoing advantages substantially without the use of damping.

FIG. 2 is a side view of the switching apparatus as viewed along line 22 of FIG. 1;

FIG. 3 is an end view of the novel switching apparatus as viewed along line 3-3 of FIG. 1;

FIG. 4 illustrates details of the contact structure of the switch shown in the preceding views;

FIG. 5 shows the relative orientation between the rotary nozzles which providefluid jets for contact-closing and contact-opening; and

PEG. '6 is a sectional view taken along line 6-6 of FIG. 4 to illustrate details of contact and rotary nozzles.

With reference now to the drawing and more particularly to FIGS. 1, 2 and 3 thereof, there is generally illustrated a representative embodiment of a high speed fluid operated switch incorporating the principles of this invention. The basic components of the switch assembly are supported upon base plate 11 and,'as shown, these components include a compressed air intake 12;an air filter 13 fitted with a reducing valve 14 together with appropriate intake and. output pressure gauges 15 and 16; a suitable drive motor 17 which may be actuated from the available power supply; and the switch mechanism 21 which is supported upon a sub-base 22.

The source of compressed air and its hose connection to air intake 12 has been omitted from the drawing. This source may comprise a conventional storage tank of dry compressed air, or a separate motor-compressor operated from the same current supply as motor 17 may be furnished with the switching unit disclosed.

. Hose 23 couples the regulated compressed air from the filter element 13 to an air inlet 24 on the switching assembly. The manner in which this compressed air is distributed within the switching assembly and used to actuate the contacts will be described in detail below. 7

Apair of spaced vertical standards 25 and 26, secured to sub-base 22, rotatably support shaft 27, which in turn carries pulley 31 atone end thereof. A complementary pulley 32 on the shaft of motor 17 and a drive belt 33 provide means for rotating shaft 27 at the desired speed.

An upright contact supporting plate 35 is rigidly affixed to sub-base 22, shaft 27 passing through a clearance hole in plate 35 without interference. A spaced pair of air distributors 36 and 37 arerigidly secured to shaft 27 on.

opposite sides of contact plate 35 between standards 25 and 26.

At this point it may be seen that, inf operation, motor 17 drives shaft 27 which in turn rotates air distributors 36 and 37. Compressed air accepted at intake 12 is applied through filter 13 and valve 14 to the switch mechanism at intake 24. By an arrangement which will be more fully described below, compressed air at the switch mechanism passes through shaft 27 andthrough air distributors 36 and 37 to actuate the switch contacts disposed upon contact plate 35.

Before proceeding with the detailed description of the contact structure,.certain observations are appropriate.

It will become, apparent that the principles of this invention are broadly applicable to a wide variety of switching systems, and that one or more pairsofcornplementary contacts may be employed depending upon the system specifications. The need for high speed switching. is most often encountered in electrical systems where a large number of circuits are to be sampled in predetermined sequence,-as for example, in telemetering arrangementswhere information on the instantaneous condition of many electrical data circuits must be transmitted to or received from a remote point. For this reason the contact arrangement chosen for illustration in the drawing includes a relatively large number of normally open contact pairs which may be individually and, sequentially closed and opened at an exceedingly high rate. I p

The exact number of contacts, of course, is a matter of design choice, but whatever the number, maximum switching speed may be achieved through the utilization 'of the techniques of this invention if the contact pairs are arranged along the arc of a circle, as in FIG. 2.

The length of are occupied by the contacts is also a matter of design to be determined by the ultimate application of the switching mechanism. For a constant speed of rotation of 'air distributors 36 and 37, as will become apparent, uniformly spaced contacts will result in a constant sampling rate and the relative angular separation of adjacent contactswill determine the time interval between successive samples. By varying the spacing between contact pairs, the time separation of successive samples may be adjusted accordingly.

If a uniform, and continuous sampling scheme is desired, the contacts may be equally spaced about a complete circle; however, in the example chosen for illustra} tion the contacts are disposed upon a circular arc of limited length. This arrangement permits uniform sequential operation of the contact pairs followed by a relatively longer interval of inactivity to complete the cycle of operation.

Turning-now to FIGS. 4, 5 and 6, the contacts and the manner in which they are actuated by the compressed 4 member 46. Each of the radial contacts is secured at its inner end to plate 35 by screws 4747. An opening 48 in each contact finger 46 is provided to enhance the fiexcent contact membersv 46 limit the outward movement of members 46. u v

For each fixed contact 44, a small threaded radial opening 52 is provided in the outer edge of plate 35.- A small conductive screw 53 fitted with a lock nut 54 is set into threaded opening 52 and a conductive extension pin 55 supports the respective fixed contact 44. A short length of wire 56, firmly secured under lock nut 54., is soldered to a respective terminal 57 from which connection may be made with the respective external circuit to be switched.

Examination of the fixed contact structure will reveal that this arrangement readily permits radial adjustment of each fixed contact 44. Thus, by loosening lock nut 56,

screw 53 may be rotated to place each fixed contact 44 at the desired spacing from complementary movable contact 45. This arrangement also facilitates replacement of any one of fixed contacts without disturbing the remainder of the switching mechanism.

The underlying principle of contact operation under the influence of a jet of fluid, such as compressed air,

has been discussed in some detail in the above-cited parent application. the present invention is bestillustrated in FIG. 6 which is a sectional view of the air distribution arrangement as applied tothe present switching mechanism.

provided with an axial bore 61 which is sealed at its upper end by a coaxial plug 62 to prevent air leakage Bore 71 communicates with the interior of shaft 27 i by means of circular recess 73 and small bore 74; and in a s1milar manner, circular recess 75 and bore 76 permit'the channelling of air from the interior of shaft 27 into opening 72 in air distributor 37.

Air distributors 36 and 37 are formed with apair of confronting nozzles 81 and 82, respectively, both of which are positioned radially so as to direct air toward a plurality of circularly spaced ducts 83 in plate 35.

Each duct 83, as best illustrated in FIGS. 4 and 6 is directly beneath the high point of respective elongate. contact member 46. These ducts serve to channel air .from nozzlev 82 to the correct contact and thus avoid,

improper operation of adjacent contacts;

H FIG. '5 illustrates the relative angular orientation .of v an distributors 36 and 37 upon shaft 27, the'arrow indi-i eating the direction of rotation in' normal operation.

air will be described more fully. FIG. 4 is a fragmentary view of contact plate 35 which is formed of a suitable insulating material with an arcuate depression '43 of rectangular cross-section. Contact engagement and disengagement occurs within depression 43. Each of the complementary contact pairs includes a fixed contact 44 and a movable contact 45, the latter being the turned-up free end of a radially disposed flexible, finger-like elongate Thus, it is apparent that nozzle 81 in air distributor 36 first passes over a given contact member 46, while upon further rotation of shaft27, nozzle 82 passes over the opposite side of the same contact member 46.

The significance of the foregoing structural details ruay now be described. Examination of FIG. 6 will illustrate that with respect to each contact pair, air delivered at intake 24 is first directed as a jet from nozzle 81 against the underside of the bowed contact member 46 while, alrnost immediately thereafter a similar air jet is directed to the opposite side of the same contact member 46 through nozzle 82 and ducti83.

The application of this basic principle to ore specifically, FIG. 6 illustrates that shaft 27 is By virtue of the resiliency of the conductive material formin'glcontact member 46, the air jet directed thereat through nozzle'81 will fiatten and hence lengthen contact-member 46, and cause the engagement of the fixed and movable contacts 44 and 45. As nozzle 81 leaves the region of contact member 46, the natural resilience of the latter member tends to restore it to the shape illustrated in FIG. 6, thus opening the circuit caused by the earlier engagement of contacts 44 and 45. This natural tendency is substantially accelerated by the force imparted upon contact member 46 by the air directed thereon by nozzle 82 through duct 83. The time required to thus separate contacts 44 and 45 is an absolute minimum.

" Analysis of the operation of a single complementarypair of contacts 44 and 45 as illustrated in FIG. 6 is now :in order. The force imparted to bowed resilient member 46 by air exhausting from nozzle 81 is considerably magnified by member 46 as it flattens and hence lengthens in the radial direction. This mode of contact operation thus provides a relatively large radial force to contacts 44 and 45 at the instant of their engagement, which in turn yields excellent electrical contact with extremely low resistance -as desired in most sensitiveinstrument applications.

But the most significant feature of the arrangement illustrated in "FIG; '6' is that the radial velocity of contact 45 during" actuation is 90 out of phase with the transverse velocity of member 46 while it is being fiattened. In other words, the central portion of elongate contact member46' achieves a maximum transverse velocity just before it is fully flattened against contact supporting plate 35. However, at this very instant of time, the radial velocity of contact 45 in the direction of contact 44 is substantially zero. Immediately thereafter, when contact member 46 is fully flattened against contact plate 35, its transverse velocity is abruptly reduced to zero, which abrupt change will create oscillations and transients within the resilient member. But since at this point in time contacts 44 and 45 are forcibly engaged, these transverse oscillations will have substantially no eflfect whatsoever upon the current carrying effectiveness of the contact junction, whereby during the major portion of the contact cycle the fixed and stationary contacts are in bounce-free engagement.

When nozzle 81 passes beyond resilient member 46 the respective contacts separate, as aforementioned, by virtue of the natural resiliency of the contact member, and further, as accelerated by air directed thereon from nozzle 82. It should be noted, of course, that at the instant of contact separation, the radially inward velocity of contact 45 is at a minimum and that this velocity of separation increases with contact separation. Although at first this may appear to be a disadvantage, it should be observed that in sensitive switching applications, such as those encountered in telemetering, both the voltages and currents are quite low so that even a low velocity separation is all that is required to satisfactorily interrupt the circuit previously made by con tact engagement.

Examination of the drawing will reveal that the angular rotation of air distributors 36 and 37 will sequentially close and open each of the respective contact pairs. With respect to any one contact pair, the cycle will occur once during each complete revolution of the air distributors.

In the drawing each of the contact pairs has been shown as normally open. It should be evident that the very same principles disclosed herein may be utilized to achieve contact opening rather than contact closure and that consequently it would be possible with relatively minor modification to make all of the contacts shown normally closed, or to arrange some of the contacts for normally open operation while others in the group are arranged for normally closed operation. All of the elongate contacts may be connected in parallel if' desired at th'eir.;inner ends to achieve the effect of single pole-multiple throw, or all of the radial contacts may be insulatedly separated to obtain completely independent circuits. The relative angular position of the surfaces of contacts 44 and 45 may be adjusted to obtain wiping action to increase contact reliability.

In the drawing, a single set of air distributors 36 and 37 has been shown. With relatively minor mechanical modification, several such air distributor pairs may be supported upon rotating shaft 27 to obtain an entirely different sequence of contact commutation. As noted earlier, these are design considerations which may be varied substantially at will to meet the requirements of the specific circuit application.

It is also clear that while this invention has been described with reference to a compressed air source, other gases may be used or liquid jets may be employed to achieve the same results. As a specific example, however, an arrangement such as shown in the drawing with movable resilient contacts approximately one inch long and several mils thick has been operated with compressed air at a pressure of 20-30 pounds per square inch to achieve sequential commutation speeds of one millisecond per total cycle of contact engagement and disengagement. Thus, a switch of this design may be utilized in a sequential sampling system to perform a function which would otherwise require an inordinate number of relatively expensive electronic switching channels. I It is clear that those skilled in the art may now make numerous modifications of and departures from the specific embodiments herein described. Consequently the invention is to be construed as limited only by the spirit and scope of the appended claims.

' What is claimed is:

1. An electrical switch comprising, a support base, a plurality of arcuately arranged insulatedly spaced stationary contacts aflixed to said base, a like plurality of elongate conductive resilient radial contact support members each having an inner end affixed to said support base and an outer free end formed with a movable contact complementary with a respective one of said stationary contacts, .each of said contact support members being curved outwardly of said base in the region between said fixed and free ends thereof whereby each of said complementary stationary and movable contact pairs are normally separated, first and second angularly separated rotary compressed fluid distributors having nozzles directed respec tively to opposite sides of one of said curved contact support members in a region intermediate said fixed and free ends thereof, and means for rotating said fluid distributors with respect to said contact support members, fluid from said nozzles being effective sequentially to'substantially flatten each of said contact support members to engage the respective stationary and movable contact pair and thereafter to accelerate restoration of said normal outward curvature of said contact support member to disengage said respective contact pair.

2. An electrical switch in accordance with claim 1 wherein the spacing between each of said contact pairs, the length and outward curvature of each of said movable contact support members are arranged whereby when actuated by said fluid each of said contact pairs engage at a relatively velocity of substantially zero.

3. An electrical switch in accordance with claim 2 wherein said spacing between each of said contact pairs and said outward curvature of each of said movable contact members are arranged to provide effective magnification of the force of said fluid upon each of said contact support members in developing the force maintaining engagement of the respective complementary contact pair.

4. An electrical switch comprising, a support base of insulating material, a stationary contact atlixed to said base, a relatively thin resilient elongate contact support member having an end aflixed to said base and an opposite free end formed with a movable contact complementary with said stationary contact, said contact support member being normally curved outwardfrom said support base in the region between said ends thereof, means for impinging a fluid under pressure against said contact support member in a "region intermediate said ends thereof for substantially flattening said contact support member against said support base and thereby eflecting a change in the length thereof for actuating said contacts, and additional means for'impinging a fluid under pressure against said contact support member in a direction to restore the normal outward curvature thereof.

5. An electrical switch comprising, a support base of insulating material, a stationary contact afiixed to said base, a relatively thin resilient elongate contact support.

member having an end affixed to said base and an opposite free end formed with a movable contact complementary withsaid stationary contact, said contact support member being normally curved outward from said support base in the region between said ends thereof, means for impinging a fluid under pressure against said contact support member in a region intermediate said ends thereof for substantially flattening said contact support member elongate conductive resilient radial contact support members each having an inner end afl'ixed to said support base and an outer free end formed with avmovable contact complementary with a respectiveone of said stationary contacts, each of saidcontact support members being curved outwardly of said base in the region between said fixed and free ends thereof whereby each of said complementary stationary and movable contact pairs are normally separated, means for impinging fluid under pressure against one of said contact members in a region intermediate the ends thereof to substantially flatten said member against said base thereby engaging the respective complementary contacts, means for sweeping saidfluid impinging means across said plurality of contact support members to sequentially engage each of said complementary contact pairs, and additional means for sequentially impinging fluid on said contact supportmembers in a direction opposite to that of fluid from said first mentioned means for accelerating the return of each of said substantially flattened contact supportmernbers to said normal outward curvature.

References Cited in the file of this patent UNITED STATES PATENTS 2,507,381 Morse May 9,1950

2,634,341 Rosen Apr. 7, 1953 2,773,665 Berger et a1. our. Dec. 11, 1956 2,773,951 Finlay et al Dec. 11, 1956 2,796,475 Finlay June 18,1957 2,852,636

Block et a1. Sept. 16, 1958 

